This invention relates to devices for polishing floors and in particular to a pad support assembly for a circular floor buffing pad.
Floor buffing or polishing machines are used for the care and maintenance of floors in commercial settings such as supermarkets, stores, office buildings, and institutions. These floor polishing machines are typically electrically powered and include a drive shaft for rotating a circular buffing pad. Over the years floor polishing machines have progressed from heavy, clumsy machines that could drive the buffing pad at 150 to 250 revolutions per minute (RPM), to what was once known as high speed machines turning at about 350 RPM, and to the present ultra high speed machines capable of producing speeds of 1000, 1500, 2000, and even 3500 RPM. Although the present ultra high speed machines are useful, there are some associated problems.
One problem associated with the use of ultra high speed machines is due to the amount of outwardly blowing wind created by the rotating buffing pad. The wind produced by the rotating pad is sufficient to blow papers off desks and light merchandise off shelves, and to generate dust and dirt. A 22 inch diameter buffing pad is capable of rotating at 2000 revolutions per minute and has a circumference speed of approximately 135 miles per hour and is capable of producing wind in volumes relative to the pad thickness at that velocity. The wind from such a rotating buffing pad is created not only by the outside edge turbulance but more importantly by air passing through the fibers of the pad in much the same manner as a centrifugal fan or squirrel cage fan. In such a device air is allowed to enter from above and below the pad to be thrown out the sides of the pad due to the centrifugal force created by the spinning action of the pad. Prior art devices, such as those disclosed in Fallen U.S. Pat. No. 4,307,480 and Bogue U.S. Pat. No. 4,809,385 suffer from this same difficiency because both these prior art devices allow air to flow into the pad from above and below.
Another problem associated with the use of ultra high speed machines is that sufficient weight is not placed on the pad for the pad to productively buff a floor surface. The older low speed polishing machines had the entire weight of the motor frame and the handle directly over the pad. Gear reduction mechanisms were necessary to reduce the speed at which the pad was rotated due to the heavy weight on the pad. Newer ultra high speed machines have a lower gear reduction ratio so the manufacturers have added wheels to support the majority of the weight of the machine. With less weight on the pad, the productivity of the machine, which uses the same pad driver design as in the older machines, is therefore decreased. Manufacturers of the ultra high speed machines have recommended that the machines be tilted to put most of the pressure on the front portion of the pad which is in contact with the floor. This is necessary due to the motor not having sufficient power to turn the pad at a higher speed if the entire periphery of the pad engages the floor. However, this method causes premature wear of the pad and presents a small buffing surface of the pad to the floor.
Still another problem associated with the use of ultra high speed polishing machines is that the buffing pads have a tendency, due to drag, to reduce the rotational speed of the machine. The slower speed of the machine reduces the size of the area which can be buffed at a particular time and requires additional passes of the machine over the area. In order to solve this problem various prior art devices, such as those disclosed in Fallen and Bogue, disclose a pad support structure which reduces the area of the buffing pad which contacts the floor to a relatively narrow peripheral annulus of the pad. Although these devices allow less drag there are other problems associated with using these devices, such as uneven and premature pad wear. Also, the contact surface of the pad by the support structure does not support the pad evenly. This results in premature wear of the pad when using these prior art devices especially directly below the teeth which engage the pad. As the pad becomes thinner, less pressure is placed on the pad material at the outside edge of the pad and this causes less of the pad to be in contact with the floor to be buffed. More passes of the pad are then required to buff the floor and more importantly additional operator time is required.
The present invention is designed to obviate and overcome many of the disadvantages and shortcomings experienced with the pad support structures hereinbefore discussed and with other pad support structures used in the past.